The invention relates to a process and arrangement for the production of a building element consisting of foamed ceramics or expanded clay aggregate.
Building elements consisting of foamed ceramics or expanded clay aggregate are included in lightweight building materials. A lightweight building element of expanded clay aggregate is produced by filling non-expanded or expanded granulate into a mold, and heating until the surfaces of the expanded granulate are sintered. The lightweight building element from expanded clay aggregate will thus display the structure of expanded granulate. In contrast hereto, an element from foamed ceramics made from unexpanded or expanded shot-shaped material or a mixture thereof, is produced by supplying heat, whereby foaming of the shot ensues in such a manner that a mass interspersed with pores will result after the burning process, this mass, when cooled down, having the appearance of a spongelike or foamlike product.
In the production of such lightweight building elements, attention must be paid to the fact that the heaped aggregate as filled into molds will--like all green ceramic stock--show strong initial shrinkage but will strongly grow upon expansion or foaming. The shrinkage will, however, not correspond to growing upon expansion, so that molded bodies of dimensional trueness can be made--if at all--only at considerable expenditure.
One possible method of producing molded bodies to exact dimensions is by initially expanding shot-shaped material, filling it into a mold when still hot and conglutinate, and compressing the conglutinate mass to the dimensions desired. (DE publication of specification No. 1 181 611).
Another process as per DE publication of specification No. 1 914 372 provides in the production of a light-weight building element for expanded or expandable granulate of approximate uniform size to be filled into a mold box and for the loosely heaped aggregate then to be heated until the surface of all granules has reached a bondable state and until commencement of the expansion process. In the subsequent expansion process, the heaped aggregate must be strongly held down so that the granulate can expand into all cavities and become a solid body of ceramically bonded expanded granules. The arrangement for implementing the known process is provided with a portable mold box having massive side walls, a bottom with sieve-like perforations and a massive cover. The cover is to prevent the heaped aggregate from occupying during the expansion process a space larger than made available by the interior space of the mold box.
The art of controlling such processes for the production of molded bodies that are true to shape and dimensions is extremely difficult and requires very complicated arrangements. Furthermore, care must be taken that the expanded body may be stripped from the mold without difficulties, i,e. that it will not adhere or bake onto the mold walls during production. This may be achieved with separating agents which, however, will not ensure the desired separating effect in every instance.
Since it is nearly impossible to manage the aforenoted difficulties in the production of lightweight building elements that are to be true to dimensions and shape, one will usually choose the method of producing lightweight building elements from expanded clay aggregate or foamed ceramics aggregate by using a steel or ceramic mold open at the top, providing the walls with a separating agent, subsequently filling the mold with heaped aggregate, heating the heaped aggregate and allowing unrestricted growing during the expansion or foaming process, cooling the molded body after expansion, stripping it from the mold and subsequently cutting or sawing from the molded body a lightweight construction element of the desired dimensions.